The South West London & St George's Mental Health NHS Trust is redeveloping the Tooting site along with the adjacent former public golf course, building a new psychiatric hospital, care homes, office and retail space and a school.
Danish practice CF Møller has designed the park to include play areas, a running trail, a pavilion, toilets, car parking, ecological areas, a formal lawn and a sports zone.
Rose gardens and extensive soft landscaping are included in the design, which is intended to improve the health and wellbeing of patients and care home residents.
Development is set to start next year and complete in 2023.
Planning permission for the scheme was given on appeal in 2012 by a Government inspector after Wandsworth Council rejected the application due to residents' concerns.